I think the most important difference between the 2 is the camber. Blend has a little early rise (on the newest model) and double time gets its name from its double camber. If you're looking for powder and soft snow the double time isn't going to do you any favors, it was designed as a park ski. With the stiffness and huge camber I bet it carves and charges well though, never tried it though so can't give you any first hand insight.
Im a little bit taller and 25 lbs heavier. I have the Blend 183, and it actually performs amazingly in boot high powder for its size. It sucks on ice tho. and its really soft. its not the best east coast ski.
Double times will charge harder and ski much better on hardpack.
Double times. I love them they are alright in pow. If you want a surface all mountain ski I'd personally probably go for one times. But they are heavier so I don't know. I love my double times and when I Demo'd one times they were amazing too.